Vegetational parameters and timing of capsule ripening of a high altitude Rhododendron (R. campanulatum) in Central Himalaya

Abstract

R.campanulatum forms krummholz close to the tree line in alpine areas. In the present study it is considered as a tree species and we concentrated our attention on capsule maturation timing and documentation of phenological events of this species which is expanding and regenerating at high altitudes. This species is relatively less studied in relation to its phenology, seed physical parameters and germination. The study was concentrated in a 5 ha area located between 3200 and 3450 m elevation in two consecutive years (2016- 2017). The overhead forest canopy was dominated by Quercus semecarpifolia towards the upper side and by Aesculus indica on the lower side. In R. campanulatum flowering started from 2nd and 3rd week of April and maximum flowering was observed between 1st and 4th week of June. Capsule formation started from 3rd and 4th week of June to 4th week of July and maturity of capsule was in the month of December to January. The colour of capsules was initially green and finally turned brown. The capsules of R. campanulatum were collected at ten days interval from the month of December up to the availability of capsules from selected sites. The number of seeds per capsule varied between 1012 and 1136. Germination was counted when visible radical had developed. The germination was maximum 42.5 ± 4.2 % at 26.3 ± 2 % moisture content. Fresh weight of capsule correlated positively with date of collection (r = 0.827; P<0.01).